Kůlna Cave, Archaeological cave in Sloup, Czech Republic.

Kůlna Cave is a tunnel-like cave piercing the rock spur of the Pustý žleb, 1 km south of Sloup. Its southern portal is 8.5 m high and 40 m wide, leading into a 92 m winding passage that climbs 7 m to a smaller northern opening, 4 m high and 10 m wide. A hatch mid-passage covers the shaft to the lower Křížovy jeskyně chambers.

The cave was inhabited by humans as early as 120,000 years ago, as revealed by archaeological excavations conducted between 1961 and 1976. These digs uncovered multiple layers of settlement and made the site significant evidence of early human presence in the region.

The lower levels discovered by Martin Kříž in 1884 are named Křížovy jeskyně (Kříž's Caves) after him. The cave's archaeological layers yielded thousands of stone tools of the Micoquien culture, mammoth and reindeer bones, and a fragment of a Neanderthal jaw. A bear skull with a spear point lodged in its palate, found in the adjoining Sloup-Šošůvka system, inspired Eduard Štorch's book Lovci mamutů.

The cave is located in the Moravian Karst approximately 23 kilometers north of Brno and forms part of the larger Sloup-Šošůvka cave system. Visitors should expect uneven surfaces and damp conditions, so sturdy footwear with good grip is recommended for safe exploration.

The underground weapons factory ran from late summer 1944 to the second half of April 1945, when it stopped because workers deserted. The concrete floor poured for it was later partly removed, and the pits left by the deep archaeological digs can still be seen in the southern part of the cave.